An air-fuel mixture for an internal combustion engine is harder to ignite when cold, leading to less complete combustion and increased emissions. Once the engine has warmed up, the cylinders may warm the air-fuel mixture sufficiently. However, at startup, the engine may have no heat to contribute to the air-fuel mixture. Cold start conditions are especially severe when the ambient air temperature is low. An intake air heating system may be used to heat air arriving at the engine. This system may be located within or prior to the intake manifold. The intake air heating system may be brought up to temperature prior to attempting to start the engine.
Heating the intake air may allow for easier ignition and may hold the fuel in suspension more effectively, leading to fewer fuel droplets falling out of suspension in the air. Intake air heating systems may allow for faster starts of the engine, may reduce startup emissions, reduce engine wear, reduce overall battery consumption during startup, and reduce startup fuel consumption.
Electrical air heater assemblies are typically housed within metallic frames (i.e., enclosures, housings, etc.). These frames include resistive metallic heating elements that emit heat based upon the current flowing through the heating elements. The current path from the outside of the frame through the heating element is electrically insulated from the frame to prevent short circuits. Typically, bushings are employed to insulate a current path from the frame. Additionally, the bushings serve to seal apertures within the frame to prevent vacuum leaks. As such, these bushings are typically in contact with the electrical connection providing the current to the heating elements and the frame. However, these bushings are manufactured from plastic or silicone. Due to the relatively high temperatures generated by the heating elements, the heat can destroy the bushings.
The background description provided here is for the purpose of generally presenting the context of the disclosure. Work of the presently named inventors, to the extent it is described in this background section, as well as aspects of the description that may not otherwise qualify as prior art at the time of filing, are neither expressly nor impliedly admitted as prior art against the present disclosure.